The invention relates to a seat occupancy detection device for a motor vehicle, in particular for a motorcycle.
Seat occupancy detection devices are generally known from the automotive field, whereas they have not been used at all up to now in the case of two-wheeled vehicles. In the automotive sector, seat occupancy detection devices are used, for example, to monitor whether a person sitting on the seat is also wearing their seatbelt. Seat occupancy detection devices of this type usually have a weight sensor which is assigned to the seat area. When the seat area is occupied by a person, the weight sensor is correspondingly triggered owing to the weight of the person. A disadvantage of such seat occupancy detection devices is that the necessary components must be introduced into the seat to provide such a seat occupancy detection device, as a result of which the complexity in terms of construction increases. Another disadvantage of such a seat occupancy detection device is that the seat occupancy detection device also responds in the event of heavy objects being placed on the seat since the seat occupancy detection device reacts to the weight which acts on the corresponding seat area.
The problem addressed by the invention is therefore to provide an alternative seat occupancy detection device which reliably detects occupancy of the seat by a person.
The problem is solved by a seat occupancy detection device according to the invention for a motor vehicle, in particular for a motorcycle, having at least one electrode of a capacitor, which is arranged in a seat area and is embodied as a wire, an electronic assembly connected to the wire, which assembly has a function generator for generating an electrical signal and an evaluation unit, wherein the electrical signal generated by the function generator can be changed by occupancy of the seat area.
The basic concept of the invention is to effectively detect seat occupancy by a person, by using the capacitive properties of a person occupying the seat area and the parasitic capacitance of the wire. The occupancy of the seat area by a person corresponds to the connection of a capacitor to the electrical circuit, as a result of which the electrical signal generated by the function generator correspondingly changes. The person occupying the seat area is thus the mating electrode to the wire, as a result of which the capacitor is formed. The electrode of the capacitor is the wire and the mating electrode is defined through the person by the ground (reference potential) of the motor vehicle. The mating electrode can thus be produced, for example, by contact of the motor vehicle frame with the foot or similar.
The wire is preferably a part of a seat heating system, wherein the wire is a heating wire. This offers the advantage that no additional wire for the seat occupancy detection device needs to be introduced into the seat area in a complex manner. In addition, the wire of a seat heating system is arranged close to the seat area, as a result of which the detection field of the electrode is less disturbed.
Furthermore, in particular, the electronic assembly is likewise a part of the seat heating system, as a result of which no further electronic components need to be installed, provided a seat heating system is present. Thus, material can be saved and a seat occupancy detection device is retrofittable when a seat heating system is present.
The heating wire can alternately, preferably periodically alternately, have a heating current applied thereto and act as electrode of the capacitor. Owing to the alternating functions of the heating wire, it is ensured that the seat occupancy detection device, on the one hand, and the seat heating system on the other hand, effectively function alongside one another, with the result that correspondingly sufficient seat area heating is provided and the seat occupancy detection device is also available when the seat heating system is switched on.
In one embodiment, a switch, in particular a MOSFET switch, is assigned to the wire. This switch can interrupt the flow of current through the wire of the seat heating system, as a result of which the wire becomes the electrode. Thus, the wire can alternately act as heating wire and as electrode. Preferably, the switch is that one which activates and deactivates the seat heating system, with the result that no additional component is necessary.
In particular, an electronic controller is provided. The electronic controller can correspondingly switch the switch embodied as a MOSFET, with the result that the switch interrupts the flow of current through the wire owing to the actuation by the electronic circuit.
The electronic assembly preferably has a constant resistor, in particular a thin-film resistor. This resistor offers the advantage that the electrical signal which is generated by the function generator is damped such that the change in the electrical signal owing to the occupancy of the seat area and the connection of the capacitor has a relatively large effect.
In a particularly preferred embodiment, at least two wires, two electronic assemblies and two seat areas are provided, wherein in each case one wire and one electronic assembly are assigned to one seat area. This offers the advantage that two seat areas can be monitored in terms of their occupancy independently of one another, for example, in the case of a motorcycle, the driver's seat area and the pillion seat area.
Furthermore, the invention relates to an assistance system for a motor vehicle, in particular a motorcycle, having a seat occupancy detection device of the type mentioned above, wherein an electronic controller is provided. The electronic controller determines from electrical signals of the seat occupancy detection device whether the seat area is occupied and activates or deactivates an assistance unit depending on the occupancy. Therefore, it is possible to correspondingly control the motor vehicle and/or an assistance unit of the motor vehicle using the seat occupancy detection device, with the result that the motor vehicle can be better controlled or can assistively intervene in auxiliary systems.
In a preferred embodiment, the assistance unit is a chassis assistance unit. The chassis assistance unit can correspondingly adjust the chassis when a two-seat occupancy is detected, for example in the case of a motorcycle by the driver's seat area and the pillion seat area. In this case, the chassis assistance unit can be the ESA system.
In another embodiment, the assistance unit is an emergency call unit, in particular an eCall system. This emergency call unit can be triggered if the seat occupancy detection device detects during driving that a previously occupied seat area is no longer occupied. In the case of a motorcycle, this would mean that the driver and/or pillion passenger had come off their seat area during driving.
In particular, the electronic controller comprises a time measuring device, with the result that the assistance unit can be activated in a delayed manner. The delay ensures that the assistance unit is not triggered immediately, rather there is a wait during a certain period of time. Thus, for example in the case of a motorcycle, it can be avoided that the emergency call unit is triggered if the driver and/or the pillion passenger stand up briefly during driving and move out of the detection field of the seat occupancy detection device.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.